Hyaluronan conjugates and uses thereof

ABSTRACT

Disclosed herein is a hyaluronan conjugate, which includes a hyaluronic acid (HA), a sex hormone, and a linker for coupling one of the disaccharide units of the HA and the sex hormone. Also disclosed herein are the uses of the hyaluronan conjugate in treating or preventing neurodegenerative diseases.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure in general relates to hyaluronic acid (HA)-sexhormone conjugates, and their uses in treating neurodegenerativediseases.

2. Description of Related Art

Neurodegenerative diseases of the central nervous system (CNS) arecharacterized by the progressive loss of structure and function ofneurons, including the death of neurons, which is mainly manifested bydementia or movement with difficulty (e.g., resting tremor, stiffness,or lumbering). Among the neurodegenerative diseases, Alzheimer's disease(AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS),Multiple Sclerosis (MS), and Huntington's disease (HD) are very commonin the neurology clinics. Neurodegenerative diseases are oftenassociated with middle to old-age populations, and are quite devastatingfor the patients and their families. Such diseases adversely impact thepatients' life quality, while at the same time pose a heavy burden tothe medical system. However, with the advent of an aging society, theprevalence rate of neurodegenerative diseases is inevitably growing up.

To date, the treatments currently available for neurodegenerativediseases are only for mitigating the symptoms or for deferring theprogression of the disease. For example, drugs like donepezil,galantamine, and rivastigmine are used to mitigate the cognitive,functional, and behavioral symptoms by delaying the catabolism ofacetylcholine released into the synaptic cleft, so as to improve thenerve conduction activities. Also, drugs like levodopa, elldopa, andamantadine are used to defer the progression of the disease and increasethe survival rate of the patients as well. Nevertheless, these drugseach has its own limitation and some even have serious side effects, andhence, the life quality of the patients remains disappointing.

In view of the foregoing, there exists in the related art a need for aneffective treatment for neurodegenerative diseases.

SUMMARY

The following presents a simplified summary of the disclosure in orderto provide a basic understanding to the reader. This summary is not anextensive overview of the disclosure and it does not identifykey/critical elements of the present invention or delineate the scope ofthe present invention. Its sole purpose is to present some conceptsdisclosed herein in a simplified form as a prelude to the more detaileddescription that is presented later.

In one aspect, the present disclosure is directed to a hyaluronanconjugate.

According to various embodiment of the present disclosure, thehyaluronan conjugate comprises a hyaluronic acid (HA) or a derivative orsalt thereof, a sex hormone and a linker that covalently coupling thesex hormone to one of the disaccharide units of the HA or HA derivativeor HA salt.

In some embodiments, the sex hormone can be estrone, estradiol, estriol,testosterone, or 11-deoxycorticosterone.

According to optional embodiments of the present disclosure, the linkerof the present hyaluronan conjugate is any of, one or more amino acids,lipid, dihydrazide-C₂-C₂₀ dicarboxylic acid, and C₂-C₂₀ dicarboxylicacids.

In one embodiment, the linker is an amino acid, such as β-alanine(β-ALA). In another embodiment, the linker is a dihydrazide-C₂-C₂₀dicarboxylic acid, e.g., an adipic acid dihydrazide (ADH)-succinate. Inyet another embodiment, the linker is a C₂-C₂₀ dicarboxylic acid; forexample, a succinic acid.

According to other embodiments of the present disclosure, the HA of thepresent hyaluronan conjugate has a degree of substitution of 0.1% to60%.

According to certain embodiments of the present disclosure, the HA ofthe present hyaluronan conjugate has a weight-average molecular weight(Mw) of about 5-500 kilodaltons (kDa). According to various embodimentsof the present disclosure, the linker is coupled to the hydroxyl group(—OH) of the sex hormone.

Another aspect of the present disclosure is directed to a method fortreating neurodegenerative diseases in a subject in need thereof.

According to some embodiments of the present disclosure, the methodcomprises the step of administering to the subject an effective amountof the present hyaluronan conjugate.

According to some embodiments of the present disclosure, the presenthyaluronan conjugate is administered to the subject via oral, nasal,intracranial, intraspinal, intrathecal, intramedullary, intracerebral,intracerebroventricular, intravenous, intraarterial, intracardial,intracutaneous, subcutaneous, transdermal, intraperitoneal, orintramuscular administration.

According to some embodiments of the present disclosure, theneurodegenerative disease that can be treated using the presenthyaluronan conjugate is Alzheimer's disease (AD), Parkinson's disease(PD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS),Huntington's disease (HD), frontotemporal dementia, epilepsy,neuropathic pain, or ataxia.

According to some embodiments of the present disclosure, the subjecttreatable by the present hyaluronan conjugate is a mammal, preferably ahuman.

Subject matters that are also included in other aspects of the presentdisclosure include the use of a hyaluronic conjugate in the manufactureof a medicament for use in the treatment of neurodegenerative diseases,as well as a hyaluronic conjugate or a pharmaceutical compositioncomprising the same for use in the treatment of neurodegenerativediseases.

Many of the attendant features and advantages of the present disclosurewill becomes better understood with reference to the following detaileddescription considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription, appended claims and the accompanying drawings, where:

FIG. 1 is scheme for synthesizing the HA-βALA-C3/C17 estradiol (HA-E2)hyaluronan conjugate, according to one working example of the presentdisclosure;

FIG. 2A and FIG. 2B show UPLC analysis results of estradiol (E2) andHA-E2, respectively, according to one working example of the presentdisclosure;

FIG. 3 show the effect of the HA-C17-E2 hyaluronan conjugate on in vitromitochondrial membrane potential (MMP) levels; according to one workingexample of the present disclosure;

FIG. 4A and FIG. 4B show the effect of the HA-E2 hyaluronan conjugate onin vivo serum and hippocampus Aβ42 level changes in APP/PS1 transgenicmice, respectively, according to one working example of the presentdisclosure;

FIG. 5 is scheme for synthesizing the HA-C17-E2 hyaluronan conjugateaccording to one working example of the present disclosure;

FIG. 6A and FIG. 6B show the in vivo effect of the HA-C17-E2 hyaluronanconjugate on the swimming distance and swimming time in OHE rats,respectively, according to one working example of the presentdisclosure;

FIG. 7A and FIG. 7B show the in vivo effect of the HA-C17-E2 hyaluronanconjugate on the swimming distance and swimming time in target quadratein OHE rats, respectively, according to one working example of thepresent disclosure;

FIG. 8A and FIG. 8B show the in vivo effect of the HA-C17-E2 hyaluronanconjugate on the swimming distance and swimming time in OHE rats,respectively, according to one working example of the presentdisclosure;

FIG. 9A and FIG. 9B show the in vivo effect of the HA-C17-E2 hyaluronanconjugate on the swimming distance and swimming time in target quadratein OHE rats, respectively, according to one working example of thepresent disclosure;

FIG. 10A and FIG. 10B are representative micrographs respectivelyshowing the in vivo effect of the HA-C17-E2 hyaluronan conjugate on thedistal apical and distal basal dendrites of pyramidal neurons inhippocampal CA1, according to one working example of the presentdisclosure;

FIG. 11A and FIG. 11B show the in vivo effect of the HA-C17-E2hyaluronan conjugate on the density of apical and basal dendritic spinesof hippocampal CA1 pyramidal neuron in OHE rats, respectively, accordingto one working example of the present disclosure; and

FIG. 12 show the in vivo effect of the HA-C17-E2 hyaluronan conjugate onthe learning ability of MPTP-treated mice, according to one workingexample of the present disclosure.

DESCRIPTION

The detailed description provided below in connection with the appendeddrawings is intended as a description of the present examples and is notintended to represent the only forms in which the present example may beconstructed or utilized. The description sets forth the functions of theexample and the sequence of steps for constructing and operating theexample. However, the same or equivalent functions and sequences may beaccomplished by different examples.

For convenience, certain terms employed in the specification, examplesand appended claims are collected here. Unless otherwise defined herein,scientific and technical terminologies employed in the presentdisclosure shall have the meanings that are commonly understood and usedby one of ordinary skill in the art.

Unless otherwise required by context, it will be understood thatsingular terms shall include plural forms of the same and plural termsshall include the singular. Also, as used herein and in the claims, theterms “at least one” and “one or more” have the same meaning and includeone, two, three, or more. Furthermore, the phrases “at least one of A,B, and C”, “at least one of A, B, or C” and “at least one of A, B and/orC,” as use throughout this specification and the appended claims, areintended to cover A alone, B alone, C alone, A and B together, B and Ctogether, A and C together, as well as A, B, and C together.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in therespective testing measurements. Also, as used herein, the term “about”generally means within 10%, 5%, 1%, or 0.5% of a given value or range.Alternatively, the term “about” means within an acceptable standarderror of the mean when considered by one of ordinary skill in the art.Other than in the operating/working examples, or unless otherwiseexpressly specified, all of the numerical ranges, amounts, values andpercentages such as those for quantities of materials, durations oftimes, temperatures, operating conditions, ratios of amounts, and thelikes thereof disclosed herein should be understood as modified in allinstances by the term “about”. Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the present disclosureand attached claims are approximations that can vary as desired. At thevery least, each numerical parameter should at least be construed inlight of the number of reported significant digits and by applyingordinary rounding techniques. Ranges can be expressed herein as from oneendpoint to another endpoint or between two endpoints. All rangesdisclosed herein are inclusive of the endpoints, unless specifiedotherwise.

The terms “treatment” and “treating” as used herein may refer to apreventative (e.g., prophylactic), curative or palliative measure. Inparticular, the term “treating” as used herein refers to the applicationor administration of the present hyaluronan conjugate or apharmaceutical composition comprising the same to a subject, who has amedical condition (e.g., a neurodegenerative disease), a symptomassociated with the medical condition, a disease or disorder secondaryto the medical condition, or a predisposition toward the medicalcondition, with the purpose to partially or completely alleviate,ameliorate, relieve, delay onset of, inhibit progression of, reduceseverity of, and/or reduce incidence of one or more symptoms or featuresof said particular disease, disorder, and/or condition. Treatment may beadministered to a subject who does not exhibit signs of a disease,disorder, and/or condition, and/or to a subject who exhibits only earlysigns of a disease, disorder and/or condition, for the purpose ofdecreasing the risk of developing pathology associated with the disease,disorder and/or condition.

The terms “subject” and “patient” are used interchangeably herein andare intended to mean an animal including the human species that istreatable by the hyaluronan conjugate described herein, pharmaceuticalcompositions comprising the same, and/or methods of the presentinvention. Accordingly, the term “subject” or “patient” comprises anymammal, which may benefit from the present disclosure. The term “mammal”refers to all members of the class Mammalia, including humans, primates,domestic and farm animals, such as rabbit, pig, sheep, and cattle; aswell as zoo, sports or pet animals; and rodents, such as mouse and rat.The term “non-human mammal” refers to all members of the class Mammalisexcept human. In one exemplary embodiment, the patient is a human. Theterm “subject” or “patient” intended to refer to both the male andfemale gender unless one gender is specifically indicated.

The term “effective amount” as used herein refers to the quantity of thepresent hyaluronan conjugate that is sufficient to yield a desiredtherapeutic response. An effective amount of an agent is not required tocure a disease or condition but will provide a treatment for a diseaseor condition such that the onset of the disease or condition is delayed,hindered or prevented, or the disease or condition symptoms areameliorated. The effective amount may be divided into one, two, or moredoses in a suitable form to be administered at one, two or more timesthroughout a designated time period. The specific effective orsufficient amount will vary with such factors as particular conditionbeing treated, the physical condition of the patient (e.g., thepatient's body mass, age, or gender), the type of mammal or animal beingtreated, the duration of the treatment, the nature of concurrent therapy(if any), and the specific formulations employed and the structure ofthe compounds or its derivatives. Effective amount may be expressed, forexample, as the total mass of the hyaluronan conjugate or the equivalentmass of the sex hormone in the hyaluronan conjugate (e.g., in grams,milligrams or micrograms) or a ratio of mass of the hyaluronan conjugateor the equivalent mass of the sex hormone in the hyaluronan conjugate tobody mass, e.g., as milligrams per kilogram (mg/kg).

The terms “application” and “administration” are used interchangeablyherein to mean the application of a hyaluronan conjugate or apharmaceutical composition of the present invention to a subject in needof a treatment thereof.

According to some examples of the present disclosure, the hyaluronanconjugate is administered twice weekly during the test period. As couldbe appreciated, the effective amount can be adjusted accordinglydepending on the interval and duration of administration. In certainembodiments, when multiple doses are administered to a subject, thefrequency of administering the multiple doses to the subject is threedoses a day, two doses a day, one dose a day, one dose every other day,one dose every third day, one dose every fourth day, one dose everyfifth day, one dose every sixth day, one dose every week, one dose everyother week, one dose monthly or one dose every other month. In certainembodiments, the frequency of administering the multiple doses to thesubject is one dose per day. In certain embodiments, the frequency ofadministering the multiple doses to the subject is two doses per day. Incertain embodiments, when multiple doses are administered to a subject,the duration between the first dose and last dose of the multiple dosesis one day, two days, four days, one week, two weeks, three weeks, onemonth, two months, three months, four months, six months, nine months,one year, two years, three years, four years, five years, seven years,ten years, fifteen years, twenty years, or the lifetime of the subject.In certain embodiments, the duration between the first dose and lastdose of the multiple doses is three months, six months, or one year. Incertain embodiments, the duration between the first dose and last doseof the multiple doses is the lifetime of the subject. In a specificembodiment, the frequency of administering the multiple doses to thesubject is three doses per week.

Also, according to the examples provided hereinbelow, the hyaluronanconjugate is administered via i.v. injection; however, this is only anillustration as to how the present invention can be implemented, and thepresent disclosure is not limited thereto.

For example, the hyaluronan conjugate can be formulated, together with apharmaceutically-acceptable excipient, into a pharmaceutical compositionsuitable for the desired mode of administration. Certain pharmaceuticalcompositions prepared in accordance with the presently disclosed andclaimed inventive concept(s) are single unit dosage forms suitable fororal, parenteral (e.g., subcutaneous, intravenous, bolus injection,intramuscular, or intraarterial), intravitreal, or transdermaladministration to a patient. Examples of dosage forms include, but arenot limited to, tablets; caplets; capsules, such as soft elastic gelatincapsules; cachets; troches; lozenges; dispersions; suppositories;ointments; cataplasms (poultices); pastes; powders; dressings; creams;plasters; solutions; patches; aerosols (e.g., nasal sprays or inhalers);gels; liquid dosage forms suitable for oral administration to a patient,including suspensions (e.g., aqueous or non-aqueous liquid suspensions,oil-in-water emulsions, or a water-in-oil liquid emulsions), solutions,and elixirs; liquid dosage forms suitable for parenteral administrationto a patient; and sterile solids (e.g., crystalline or amorphous solids)that can be reconstituted to provide liquid dosage forms suitable forparenteral administration to a patient. As could be appreciated, thesepharmaceutical compositions are also within the scope of the presentdisclosure.

The phrase “pharmaceutically acceptable excipient” as used herein meansa pharmaceutically acceptable material, composition or vehicle, such asa liquid or solid filler, diluent, carrier, solvent or encapsulatingmaterial, involved in carrying or transporting the subject agents fromone organ, or portion of the body, to another organ, or portion of thebody. Each excipient must be “acceptable” in the sense of beingcompatible with the other ingredients of the formulation. Thepharmaceutical formulation contains a compound of the invention incombination with one or more pharmaceutically acceptable ingredients.The excipient can be in the form of a solid, semi-solid or liquiddiluent, cream or a capsule. These pharmaceutical preparations are afurther object of the invention. Usually, the amount of active compoundsis between 0.1-95% by weight of the preparation, preferably between0.2-20% by weight in preparations for parenteral use and preferablybetween 1 and 50% by weight in preparations for oral administration. Forthe clinical use of the methods of the present invention, thepharmaceutical composition of the invention is formulated intoformulations suitable for the intended route of administration.

The term “degree of substitution (DS)” of the HA conjugate, as usedherein, is the average ratio of substituent groups (i.e., the sexhormone) attached per disaccharide unit of the HA.

As used herein, the term “hyaluronic acid” (HA) (also called hyaluronateor hyaluronan) is an anionic, nonsulfated glycosaminoglycan composed ofa repeating sequence of disaccharide units, specifically a D-glucuronicacid and a N-acetyl-D-glucosamine (−4GlcUAβ1-3GlcNAcβ1-). Its molecularweight can range from 379 Dalton (Da) (the single disaccharide unit) toover millions of daltons. HA is involved in cell motility and immunecell adhesion by interaction with the cell surface receptor forhyaluronan-mediated motility (RHAMM) and CD44. The term “HA derivative”refers to an HA having any modification on the hydroxyl, carboxyl, amideor acetylamino groups of one or more disaccharide units of the HA.

As used herein, the term “salt” refers to any and all salts, andencompasses pharmaceutically acceptable salts. The term“pharmaceutically acceptable salt” refers to those salts which are,within the scope of sound medical judgment, suitable for use in contactwith the tissues of humans and lower animals without undue toxicity,irritation, allergic response, and the like, and are commensurate with areasonable benefit/risk ratio. Pharmaceutically acceptable salts arewell known in the art.

As used herein, the term “linker” means a chemical moiety (e.g., achemical bond form between two functional groups) that connects twoparts of a conjugate. In the present disclosure, the linker may be anychemical moiety present between the sex hormone and the HA. In someembodiments of the present disclosure, the linker may be digestedchemically or enzymatically; alternatively, it may degradespontaneously.

According to preferred embodiments of the present disclosure, thepresent hyaluronan conjugate is formulated into a “modified release(MR)” formulation, such as extended-release (ER), controlled-release(CR), sustained-release (SR), prolonged release (PR), long-actingrelease (LAR) and delayed-release (DR) drug products. As opposed toconventional dosage forms that often give prompt release of the drugsubstance thereby showing fluctuations in drug concentration in the bodyand necessitating multiple dosing to maintain the therapeutic level ofthe drug substance, in modified release dosage forms, releasecharacteristics of time course and/or location of the drug substance arechosen to accomplish the desired therapeutic objectives not offered byconventional dosage forms. The terminologies with respect to the dosageforms shall have their ordinary meanings as recognized and used bypersons having ordinary skill in the art. For example, the term“extended-release” is a dosage form that allows at least a twofoldreduction in dosage frequency as compared to that drug presented as animmediate-release (conventional) dosage form. The term “controlledrelease” refers to dosage forms from which drug substance may bedelivered over a prolonged period of time; in the case of injectabledosage forms, this period may vary from day to months. The term“sustained release” refers to the release of the drug substance at apredetermined rate leading to a constant plasma concentration for aperiod of time.

The present disclosure is based, at least in part, on an unexpecteddiscovery that HA-sex hormone conjugates exhibit desirable therapeuticeffect on treating various neurodegenerative diseases, while at the sametime reduce the unwanted side effects caused by sex hormones acting onother organs, such as breast and heart.

Accordingly, the first aspect of the present disclosure is directed to ahyaluronan conjugate that comprises a hyaluronic acid (HA) or aderivative or a salt thereof, a sex hormone, and a linker for couplingthe sex hormone to one of the disaccharide units of the HA or the HAderivative or HA salt.

For example, the sex hormone can be any of estrone (E1), estradiol (E2),estriol (E3), testosterone (T), and 11-deoxycorticosterone (11-DOC).

According to various embodiments, the linker may be one or more aminoacid residues, a lipid, a dihydrazide-C₂-C₂₀ dicarboxylic acid, or aC₂-C₂₀ dicarboxylic acid. In present disclosure, the linker serves as anarm or a spacer for connecting the HA and the sex hormone. The linkerengages, on one side, the HA via a hydroxyl, carboxyl, amide, oracetylamino group linkage, and, on the other side, the sex hormone viaany possible covalent bond.

In some embodiments, the linker is a single amino acid residue, such as,alanine (Ala; preferably, β-alanine), arginine (Arg), asparagine (Asn),aspartic acid (Asp), cysteine (Cys), glutamic acid (Glu), glutamine(Gln), glycine (Gly), histidine (His), isoleucine (Ilu), leucine (Leu),lysine (Lys), methionine (Met), phenylalanine (Phe), proline (Pro),serine (Ser), threonine (Thr), tryptophan (Trp), tyrosine (Tyr), valine(Val), γ-abu (4-aminobutanoic acid), δ-aminovaleric acid(5-aminopentanoic acid), ε-aminocaproic acid (6-aminohexanoic acid),7-aminoheptanoic acid, 8-aminooctanoic acid, and 11-aminoundecanoicacid. In some embodiments, the linker may be a short peptide having twoto 100 amino acid residues. For example, the linker may be a flexiblepeptide having a sequence of (G_(n)S)_(m), where n and m areindependently a number between 1 to 4.

In some embodiments, a lipid linker is preferred. Such lipid linkershave a hydrophilic polar head group and a hydrophobic chain.

In some embodiments, the linker is a linear or branched, aliphatic,aromatic or araliphatic C₂-C₂₀ dicarboxylic acids, which may be aderivative of, for example, oxalic acid, malonic acid, succinic acid,glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid,sebacic acid, dodecanedioic acid, brassylic acid, thapsic acid, diabolicacids, crocetin, maleic acid, fumaric acid, glutaconic acid,2-decenedioic acid, traumatic acid, muconic acid, glutinic acid,citraconic acid, mesaconic acid, itaconic acid, tartronic acid,mesoxalic acid, malic acid, tartaric acid, oxaloacetic acid, asparticacid, α-hydroxyglutaric acid, arabinaric acid, acetonedicarboxylic acid,α-ketoglutaric acid, glutamic acid, diaminopimelic acid, saccharic acid,phthalic acid, isophthalic acid, terephthalic acid, diphenic acid, and2,6-naphthalenedicarboxylic acid.

A dihydrazide-C₂-C₂₀ dicarboxylic acid-based linker generally has twomoieties, i.e., a dihydrazide and C₂-C₂₀ dicarboxylic acid, in which onecarboxylate group of the C₂-C₂₀ dicarboxylic acid is covalently bondedwith one hydrazide group of the dihydrazide. Examples for thedihydrazide moiety include, but are not limited to adipic aciddihydrazide (ADH), sebacic acid dihydrazide (SDH), valine dihydrazide(VDH), isophthalic dihydrazide (IDH), carbodihydrazide (CDH),icosanedioic acid dihydrazide (LDH), succinic dihydrazide, adipicdihydrazide, dihydrazide sulfoxide, oxalic dihydrazide, and pimelic aciddihydrazide. Illustrative examples described above in connection withthe C₂-C₂₀ dicarboxylic acid linker are also suitable for use as thedicarboxylic acid moiety for dihydrazide-C₂-C₂₀ dicarboxylic acid-basedlinkers.

The present linker also encompasses an amino-C2-C20 dicarboxylicacid-based linker, which has two moieties, i.e., one or more amino acidsand C2-C20 dicarboxylic acid. Illustrative examples described above inconnection with the amino acid residues and the C2-C20 dicarboxylic acidlinker are also suitable for use to form such as t amino-C2-C20dicarboxylic acid-based linker. As an example, rather than a limitation,the amino-C2-C20 dicarboxylic acid-based linker can be an ALA-succinatelinker.

According to some embodiments of the present disclosure, the HA of thepresent hyaluronan conjugate has a weight-average molecular weight (Mw)ranging from about 5 kDa to about 500 kDa, for example, about 5, 6, 7,8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85,90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220,230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360,370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500kDa.

According to some embodiments of the present disclosure, the HA of thepresent hyaluronan conjugate may be in an unsubstituted (i.e., the HAper se) or a substituted (i.e., the HA derivative) form, or may be asalt thereof. As described above, HA can be modified on its functionalgroups such as hydroxyl, carboxyl, amide or acetylamino groups. HA canbe modified by esterification, grafting and/or hydrophobization on itsfunctional groups (i.e., hydroxyl, carboxyl, amide or acetylaminogroups) as described above through reaction with a series of chemicalagents. Exemplary HA derivatives are ethylsulfonated HA, deacetylatedHA, or hydrazide-modified HA. In one example of the present disclosure,the HA of the present hyaluronan conjugate is in an unsubstituted form.In another example of the present disclosure, the HA of the presenthyaluronan conjugate is in a substituted form.

According to various embodiments of the present disclosure, the presenthyaluronan conjugate has a degree of substitution with the sex hormoneof 0.1 to 60%. For example, the DS may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5,8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,or 60%.

The conjugated disaccharide unit of some representative hyaluronicconjugates of the present invention are summarized in Table 1 below;however, the present invention is not limited thereto. As could beappreciated, the stereoisomers of the illustrative sex hormone shown inTable 1 are also envisaged by the present inventors.

TABLE 1 Sex No. Chemical Structure Hormone Linker I

E1 Succinate II

E1 ADH- Succinate III

E1 β-Ala IV

E1 β-Ala- succinate V

E2 ADH- succinate VI

E2 ADH- succinate VII

E2 Succinate VIII

E2 Succinate IX

E2 β-Ala- succinate X

E2 β-Ala- succinate XI

E2 β-Ala XII

E2 β-Ala XIII

E3 ADH- succinate XIV

E3 ADH- succinate XV

E3 ADH- succinate XVI

E3 Succinate XVII

E3 Succinate XVIII

E3 Succinate XIX

E3 β-Ala- succinate XX

E3 β-Ala- succinate XXI

E3 β-Ala XXII

E3 β-Ala- succinate XXIII

E3 β-Ala XXIV

E3 β-Ala XXV

11-DOC ADH- succinate XXVI

11-DOC Succinate XXVII

11-DOC β-Ala XXVIII

11-DOC β-Ala- succinate XXIX

T ADH- succinate XXX

T Succinate XXXI

T β-Ala XXXII

T β-Ala- succinate

According to various embodiments of the present disclosure, the linkerhas one functional group reactable with the hydroxyl group of the sexhormone and another functional group reactable with the carboxylategroup or the hydroxyl group of one disaccharide unit of the HA, therebyconjugating the sex hormone with the HA. However, the present inventionis not limited thereto. In other embodiments, the sex hormone may befirst modified with a chemical moiety reactable with the linker.

Also encompassed within the present disclose is a composition whichcomprises the present hyaluronan conjugate described above; and apharmaceutically-acceptable excipient.

Acceptable carriers are nontoxic to recipients at the dosages andconcentrations used. According to some embodiments of the presentdisclosure, the pharmaceutically-acceptable excipient may comprisebuffers such as phosphate, citrate, and other organic acids;antioxidants including ascorbic acid and methionine; preservatives (suchas octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride;benzalkonium chloride, benzethonium chloride; phenol, butyl or benzylalcohol; alkyl parabens such as methyl or propyl paraben; catechol;resorcinol; cyclohexanol; 3-pentanol; benzoates, sorbate and m-cresol);low molecular weight (less than about 10 residues) polypeptides;proteins, such as serum albumin, gelatin, or immunoglobulins;hydrophilic polymers such as polyvinylpyrrolidone; amino acids such asglycine, glutamine, asparagine, histidine, arginine, serine, alanine orlysine; monosaccharides, disaccharides, and other carbohydratesincluding glucose, mannose, or dextrans; chelating agents such as EDTA;sugars such as sucrose, mannitol, trehalose or sorbitol; salt-formingcounter-ions such as sodium; metal complexes (e.g., Zn-proteincomplexes); and/or non-ionic surfactants such as Tween™, Pluronics™ orpolyethylene glycol (PEG) (See Remington: The Science and Practice ofPharmacy 20th Ed. (2000) Lippincott Williams and Wilkins, Ed. K. E.Hoover).

The pharmaceutical compositions described herein can be in unit dosageforms such as tablets, pills, capsules, powders, granules, gels, orsolutions or suspensions, for oral or parenteral administration.

The present hyaluronan conjugate is present in the pharmaceuticalcomposition at a level of about 0.1% to 99% by weight, based on thetotal weight of the pharmaceutical composition. In some embodiments, thepresent hyaluronan conjugate is present at a level of at least 1% byweight, based on the total weight of the pharmaceutical composition. Incertain embodiments, the present hyaluronan conjugate is present at alevel of at least 5% by weight, based on the total weight of thepharmaceutical composition. In still other embodiments, the presenthyaluronan conjugate is present at a level of at least 10% by weight,based on the total weight of the pharmaceutical composition. In stillyet other embodiments, the present hyaluronan conjugate is present at alevel of at least 25% by weight, based on the total weight of thepharmaceutical composition.

Pharmaceutical compositions described herein can be prepared by anymethod known in the art of pharmacology. In general, such preparatorymethods include bringing the present hyaluronan conjugate describedherein (i.e., the “active ingredient”) into association with a carrieror excipient, and/or one or more other accessory ingredients, and then,if necessary and/or desirable, shaping, and/or packaging the productinto a desired single- or multi-dose unit. A “unit dose” is a discreteamount of the pharmaceutical composition comprising a predeterminedamount of the active ingredient. The amount of the active ingredient isgenerally equal to the dosage of the active ingredient which would beadministered to a subject and/or a convenient fraction of such a dosage,such as one-half or one-third of such a dosage.

The present hyaluronan conjugate provided herein is typically formulatedin dosage unit form for ease of administration and uniformity of dosage.It will be understood, however, that the total daily usage of thecompositions described herein will be decided by a physician within thescope of sound medical judgment. The specific therapeutically effectivedose level for any particular subject or organism will depend upon avariety of factors including the disease being treated and the severityof the disorder; the activity of the specific active ingredientemployed; the specific composition employed; the species, age, bodyweight, general health, sex, and diet of the subject, severity of theside effects or disorder; the time of administration, route ofadministration, and rate of excretion of the specific active ingredientemployed; the duration of the treatment; drugs identity of theparticular present hyaluronan conjugates used in combination orcoincidental with the specific active ingredient employed; and likefactors well known in the medical arts.

As such, also encompassed within the scope of the present disclosure isthe use of the present hyaluronan conjugates in manufacturing apharmaceutical composition, wherein the pharmaceutical composition isused for treating a neurodegenerative disease in a subject in need.

Another aspect of the present disclosure is to provide a method fortreating or reducing the risk of a neurodegenerative disease in asubject, comprising the step of administering to the subject aneffective amount of the aforementioned hyaluronan conjugate or apharmaceutical composition comprising the same.

The present hyaluronan conjugates described herein are useful intreating or reducing the risk for a neurodegenerative disease in asubject (e.g., a human patient having, suspected of having, or at riskfor the neurodegenerative disease). In some embodiments, theneurodegenerative diseases include, but are not limited to, Alzheimer'sdisease, Parkinson's disease, amyotrophic lateral sclerosis, multiplesclerosis, Huntington's disease, frontotemporal dementia, epilepsy,neuropathic pain, or ataxia.

The present hyaluronan conjugates provided herein, or a compositioncomprising such, can be administered by a suitable route as known tothose skilled in the art, including oral, nasal, intracranial,intraspinal, intrathecal, intramedullary, intracerebral,intracerebroventricular, intravenous, intraarterial, intracardial,intracutaneous, subcutaneous, transdermal, intraperitoneal, orintramuscular administration. Specifically contemplated routes includeoral administration, intravenous administration (e.g., systemicintravenous injection), regional administration via blood and/or lymphsupply, and/or direct administration to an affected site. In general,the most appropriate route of administration will depend upon a varietyof factors including the nature of the agent (e.g., its stability in theenvironment of the gastrointestinal tract), and/or the condition of thesubject (e.g., whether the subject is able to tolerate oraladministration).

The exact amount of the present hyaluronan conjugates or apharmaceutical composition comprising such required to achieve aneffective amount will vary from subject to subject, depending, forexample, on factors as described above. An effective amount may beincluded in a single dose (e.g., single oral dose) or multiple doses(e.g., multiple oral doses). In certain embodiments, when multiple dosesare administered to a subject, the frequency of administering themultiple doses to the subject is three doses a day, two doses a day, onedose a day, one dose every other day, one dose every third day, one doseevery week, one dose every other week, one dose monthly or one doseevery other month. In certain embodiments, the frequency ofadministering the multiple doses to the subject is one dose per day. Incertain embodiments, the frequency of administering the multiple dosesto the subject is two doses per day. In certain embodiments, whenmultiple doses are administered to a subject, the duration between thefirst dose and last dose of the multiple doses is one day, two days,four days, one week, two weeks, three weeks, one month, two months,three months, four months, six months, nine months, one year, two years,three years, four years, five years, seven years, ten years, fifteenyears, twenty years, or the lifetime of the subject. In certainembodiments, the duration between the first dose and last dose of themultiple doses is three months, six months, or one year. In certainembodiments, the duration between the first dose and last dose of themultiple doses is the lifetime of the subject. In a specific embodiment,the frequency of administering the multiple doses to the subject isthree doses per week.

For example, according to some working examples of the presentdisclosure, the effective amount expressed as the equivalent mass of thesex hormone in the hyaluronan conjugate for treating variousneurodegenerative diseases in rats (about 150 grams) is about 100 ng/kgbody weight to 10 μg/kg body weight. Therefore, the effective amount fortreating rats in terms of the sex hormone in the hyaluronan conjugate isabout 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112,113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154,155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168,169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182,183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196,197, 198, 199, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300,310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440,450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580,590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720,730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860,870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, or 990 ng/kgbody weight/dose, or 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7,7.5, 8, 8.5, 9, 9.5, or 10 μg/kg body weight/dose.

Also, the effective amount for treating mice (about 20 grams) in termsof the equivalent mass of the sex hormone in the hyaluronan conjugate isabout 150 ng/kg body weight to 15 μg/kg; for example, about 150, 151,152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165,166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179,180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193,194, 195, 196, 197, 198, 199, 200, 210, 220, 230, 240, 250, 260, 270,280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410,420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550,560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690,700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830,840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970,980, or 990 ng/kg body weight/dose, or 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5,5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5,13, 13.5, 14, 14.5, or 15 μg/kg body weight/dose.

In an adult human weighting approximately 60 kg, the human equivalentdose (HED) derived from the above-described doses for rats (conversionfactor: 0.16) is about 16 ng/kg body weight to 1.6 μg/kg bodyweight/dose, in terms of the equivalent mass of the sex hormone in thehyaluronan conjugate. On the other hand, the HED based on the mice dose(conversion factor: 0.08) is about 12 ng/kg body weight to 1.2 μg/kgbody weight/dose. In sum, the HED is about 12 ng/kg body weight to 1.6μg/kg body weight/dose, in terms of the equivalent mass of the sexhormone in the hyaluronan conjugate.

As could be appreciated, the dosage ranges described above is providedas a guidance for the administration of provided pharmaceuticalcompositions to an adult. The amount to be administered to, for example,a child or an adolescent can be determined by a medical practitioner orperson skilled in the art and can be lower or the same as thatadministered to an adult. Considering the age, weight, and healthcondition of the patient, the effective amount for a human subject canbe about 6 ng/kg body weight/dose to 3 μg/kg body weight/dose, in termsof the equivalent mass of the sex hormone in the hyaluronan conjugate.Specifically, the effective amount of the equivalent mass of the sexhormone in the present hyaluronan conjugate for a human subject may be6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55,56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135,136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149,150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163,164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177,178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,192, 193, 194, 195, 196, 197, 198, 199, 200, 210, 220, 230, 240, 250,260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390,400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530,540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670,680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810,820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950,960, 970, 980, or 990 ng/kg body weight/dose, or 1, 1.5, 2, 2.5, or 3μg/kg body weight/dose.

As could be appreciated by persons having ordinary skill in the art, theeffective amount of the present hyaluronan conjugate for treatingvarious neurodegenerative can be determined from the above-mentionedequivalent mass of the sex hormone in the hyaluronan conjugate inconjunction with the drug load (or the degree of substitution) of thehyaluronan conjugate. And each of the effective amounts of the presenthyaluronan conjugate thus determined is deemed to be part of the presentdisclosure.

For example, according to some working examples of the presentdisclosure, the effective amount of the hyaluronan conjugate fortreating various neurodegenerative diseases in rats (about 150 grams) isabout 25 to 2,500 μg/kg body weight, and in mice (about 20 grams) isabout 1 to 100 μg/kg. Therefore, the effective amount of the presenthyaluronan conjugate for treating neurodegenerative diseases in rats isabout 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58,59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76,77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94,95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109,110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123,124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137,138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151,152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165,166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179,180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193,194, 195, 196, 197, 198, 199, 200, 210, 220, 230, 240, 250, 260, 270,280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410,420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550,560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690,700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830,840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970,980, 990, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900,2000, 2100, 2200, 2300, 2400, or 2500 μg/kg body weight/dose. Also, theeffective amount of the present hyaluronan conjugate for treating miceis about 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5,9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,98, 99, or 100 μg/kg body weight/dose.

Similarly, in an adult human weighting approximately 60 kg, the HED ofthe present hyaluronan conjugate derived from the above-described dosesfor mice (conversion factor: 0.08) is about 80 ng/kg body weight/dose to8 μg/kg body weight/dose, and for rat (conversion factor: 0.16), 4 to400 μg/kg body weight/dose. In sum, the HED for the present hyaluronanconjugate is about 80 ng/kg body weight to 400 μg/kg body weight/dose.Considering the age, weight, and health condition of the patient, theeffective amount for a human subject can be about 40 ng/kg bodyweight/dose to 700 μg/kg body weight/dose.

Specifically, the effective amount for a human subject may be 40, 41,42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77,78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110,111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124,125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138,139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152,153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166,167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180,181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194,195, 196, 197, 198, 199, 200, 210, 220, 230, 240, 250, 260, 270, 280,290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420,430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560,570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700,710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840,850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, or990 ng/kg body weight/dose, or 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5,6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55,56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135,136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149,150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163,164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177,178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,192, 193, 194, 195, 196, 197, 198, 199, 200, 210, 220, 230, 240, 250,260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390,400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530,540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670,680, 690, or 700 μg/kg body weight/dose.

Dose ranges as described herein provide guidance for the administrationof provided pharmaceutical compositions to an adult. The amount to beadministered to, for example, a child or an adolescent can be determinedby a medical practitioner or person skilled in the art and can be loweror the same as that administered to an adult.

The present hyaluronan conjugate, as described herein, can beadministered in combination with one or more additional pharmaceuticalagents (e.g., therapeutically active agents) useful in treating and/orreducing the risk for a neurodegenerative disease. In certainembodiments, the present hyaluronan conjugate described herein and theadditional pharmaceutical agent show a synergistic effect on treating aneurodegenerative disease. The present hyaluronan conjugate can beadministered concurrently with, prior to, currently with, or subsequentto one or more additional pharmaceutical agents, which may be useful as,e.g., combination therapies in treating and/or reducing the risk for aneurodegenerative disease in a subject.

Pharmaceutical agents include therapeutically active agents. Eachadditional pharmaceutical agent may be administered at a dose and/or ona time schedule determined for that pharmaceutical agent. The additionalpharmaceutical agents may also be administered together with each otherand/or with the composition comprising the present hyaluronan conjugatedescribed herein in a single dose or administered separately indifferent doses. In certain embodiments, the additional pharmaceuticalagent is an agent for treating and/or reducing the risk for aneurodegenerative disease can be an agent for treating Alzheimer'sdisease (AD), includes, but is not limited to, donepezil, rivastigmine,galantamine, memantine, selfotel, midafotel, tacrine, selegiline, andvitamin E.

According to some embodiments of the present disclosure, the subjecttreatable by the present hyaluronan conjugate is a mammal. In someexamples, the subject is a mouse or a rat. In other examples, thesubject is a human.

Also encompassed by the present disclosure are kits for use in treatingany of the target neurodegenerative diseases described herein. The kitsprovided herein may comprise the present hyaluronan conjugates describedherein, or a pharmaceutical composition comprising such. Optionally, thekit may further comprise one or more additional pharmaceutical agents asdescribed herein.

The following Examples are provided to elucidate certain aspects of thepresent invention and to aid those of skilled in the art in practicingthis invention. These Examples are in no way to be considered to limitthe scope of the invention in any manner. Without further elaboration,it is believed that one skilled in the art can, based on the descriptionherein, utilize the present invention to its fullest extent. Allpublications cited herein are hereby incorporated by reference in theirentirety.

EXAMPLES Example 1

Synthesis and characterization of HA-βALA-Estradiol

In this example, a mixture containing both HA-βALA-C17 estradiol (Aform) and HA-βALA-C3 estradiol (B form) was synthesized in accordancewith steps described in Scheme I (FIG. 1 ).

Briefly, Boc-β-alanine (2.92 mmole, 552 mg), DCC (3.40 mmole, 702 mg),and 4-dimethylaminopyridine (DMAP) (3.04 mmole, 372 mg) were added intoa solution of estradiol (2.75 mmole, 750 mg) in dichloromethane (DCM)(250 mL), and the mixture was stirred overnight at room temperature(RT). The solvent was removed under vacuum and the precipitate was thendissolved by methanol. The resulting mixture was added with 10% K₂CO₃solution (methanol: 10% K₂CO₃=1:1) and stirred overnight at RT. Then,the mixture was concentrated and extracted by DCM and water. Most DCMwithin the mixture was removed under vacuum, and the precipitate withinthe mixture was filtered out. The filtrate was washed by DCM andconcentrated under vacuum. The residue was washed by acetone, and theprecipitate was filtered out. After that, the filtrate was concentrated,and then purified by silica gel column chromatography (eluent:acetone:hexane=1:1) to obtain the product, Boc-β-alanine-estradiol.

The stepwise procedure for the synthesis of HA-βALA-Estradiol was asfollows: A bottle: Boc-β-alanine-estradiol (0.19 mmole, 83 mg) wasdissolved in DCM (1 mL), and the solution was stirred at RT. Thesolution was added with trifluoroacetic acid (TFA) (0.2 mL, 2 mmole),and the reaction lasted for 4 hours; then Na₂CO₃ solution (55 mg/mL) wasadded dropwisely into the solution in ice bath until no bubble wasreleased from the solution. Then, DCM was removed from the solutionunder vacuum. Ethyl cyanohydroxyiminoacetate (oxyma) (1.39 mmole, 250mg) and dimethyl sulfoxide (DMSO) (20 mL) were then added to theresidue, and the solution was stirred at RT. B bottle: HA solution (500mg/25 mL) was mixed with DMSO (20 mL), and the mixture was stirred untilthe temperature went back to RT. The solution of B bottle was pouredinto A bottle, and the mixture was thoroughly mixed.N,N′-diisopropylcarbodiimide (DIC) (2.58 mmole, 326 mg) was added intothe mixture under the level, and the reaction was lasted for 24 hours.After that, the reaction mixture was purified by dialysis (3500molecular weight cut off (MWCO) dialysis bag, 10 L of water for 12hours; 1 L of 0.3M NaCl for 12 hours, twice; and 10 L of water for 12hours, 5 times), and then the fraction within the dialysis bag wascollected and lyophilized.

The HA-βALA-C3/C17 estradiol (HA-E2) thus synthesized was confirmed byUPLC (Acquity UPLC and PDA detector (Waters)); column: ACQUITY UPLCBEH200 SEC column (1.7 μm, ID 4.6 mm×150 mm); flow rate: 0.3 mL/min;injection volume: 50 μl; detector: UV 280 nm; temperature: for column,25° C., for autosampler, 20° C.; running time: 18 minutes; relativeretention time: for HA-E2 (HA-βALA-C3/C17 estradiol), 2.7, for E2(estradiol), 10.1. For calculation, linear regression was applied togenerate a standard curve y=mx+b, wherein: x is E2 concentration inμg/ml; y is the peak area for all standards; m is the slope of standardcurve; b is the intercept of standard curve; and, acceptable correlationcoefficient (r2) for standard curve is ≥0.9950.

FIG. 2A and FIG. 2B respectively show the UPLC profile of estradiol (E2)and HA-βALA-C3/C17 estradiol (HA-E2).

Example 2

Effect of Hyaluronan Conjugates on Neural Cell Uptake

In this example, paired set of experiments were performed to investigatethe neural cell (human neuroblastoma SH-SY5Y cells) uptake of thepresent hyaluronan conjugates. The results (data not shown) indicatethat the neural cells uptake more HA-E1 conjugate than estrone alone,the same also applies to other paired sets, including, HA-E2 conjugatevs estradiol alone, HA-E3 conjugate vs estriol alone, HA-testosteroneconjugate vs testosterone alone, and HA-deoxycorticosterone vs11-deoxycorticosterone alone.

Based on the preliminary results from the paired-set experiments above,HA-E2 and E2 were subject to further analysis.

It is known that estrogen can help maintain the viability of neuralcells, and one manifestation of this phenomenon is the upregulation ofATP level in cells. Since mitochondrial membrane potential is thedriving force for mitochondrial ATP synthesis, neural cells wererespectively treated with HA-C17-E2 and E2, and the cellularmitochondrial membrane potential level was then measured.

Briefly, human neuroblastoma SH-SY5Y cells were grown in Eagle's minimumessential medium (EMEM) supplemented with 10% heat-inactivated fetalbovine serum (FBS), 100 units/mL penicillin, and 100 μg/mL streptomycin,at 37° C. in a humidified 5% CO₂ incubator. For measurement ofmitochondrial membrane potential, SH-SY5Y cells were incubated togetherwith E2 (0.14, 0.34, 0.68, and 1.36 μg/mL), HA (6.48, 16.19, 32.38, and64.76 μg/mL), or HA-C17-E2 (6.48, 16.19, 32.38, and 64.76 μg/mL,respectively equivalent to the E2 concentration) for 18 hours.

Tetramethylrhodamine, methyl ester (TMRM) is a cell-permeant, cationic,red-orange fluorescent dye that is readily sequestered by activemitochondria. Cells were trypsinized and resuspended in 0.5 mL of PBScontaining 100 nM of TMRM (Molecular Probes, Eugene, Oreg.). Afterincubation for 30 minutes at 37° C. in the dark, cells were immediatelytransferred to a tube on ice, and the fluorescence intensity wasmeasured by flow cytometry using FL2 detector.

A FACS Calibur flowcytometer (Becton Dickinson, Bedford, Mass.) equippedwith a 488-nm argon laser was used for the flow cytometric analysis.Forward and side scatters were used to establish size gates and excludecellular debris from the analysis. The excitation wavelength was set at488 nm. In each measurement, a minimum of 20,000 cells were analyzed.Data were acquired and analyzed using the Cell Quest software (BectonDickinson). Relative change in the mean fluorescence intensity wascalculated as the ratio between mean fluorescence intensity in thechannel of the treated cells and that of the control cells.

As shown in FIG. 3 , the treatment of HA-C17-E2 (32.38 μg/mL, equivalentto 0.68 μg/mL E2) or HA-C17-E2 (64.76 μg/mL, equivalent to 1.36 μg/mLE2) is capable of increasing the mitochondrial membrane potential levelsin cells, compared to the control group and HA only or E2 onlytreatment.

Example 3

Effect of Hyaluronan Conjugates on Amyloid Beta Expression

In this example, effects of the present hyaluronan conjugate on severalindexes of Alzheimer's disease in APP/PS1 transgenic mice includingamyloid plaque formation and distribution and expression level of Aβ42,were investigated. APP/PS1 transgenic mice overproduce amyloid beta (Aβ)and are extensively used as the animal model of Alzheimer's disease.

APPswe/PS1dE9 (APP/PS1) transgenic mice were obtained from Jackson lab.All the procedures were performed in accordance with the specificationsof the Animal Experimental Center of the National Research Institutionof Chinese Medicine (IACUC No. 106-417-4).

The APP/PS1 mice of 8 week-old were intravenously administered 0.206mg/kg E2 or 12.5 mg/kg HA-E2 (equivalent to 0.206 mg/kg E2) or thecontrol vehicle three times per week, for a total of 8 weeks. On the7^(th) week, 5-bromo-2′-deoxyuridine (BrdU) of a dose of 50 mg/Kg/daywas administered intraperitoneally daily for 7 days. The animals werethen sacrificed by anesthesia with administered intraperitoneallyZoletil/Xylazine (20 mg/Kg: 5 mg/Kg). After deep anesthesia, blood wascollected from the heart, centrifuged at 13,000 rpm to isolate theserum. After perfusion with pH 7.4 saline, the cortex and hippocampus ofthe hemisphere of the brain were surgically removed, homogenized, andstored at −30° C. The other half of the brain was fixed by immersed in4% formaldehyde for 3 to 7 days, followed by dehydration with 20% and30% sucrose for 3 to 7 days. The brain tissues were frozen for furthersectioning.

Two-step sequential extraction of the brain Aβ using 2% SDS and 70%formic acid (FA) (Sigma) was performed. Briefly, the cortical homogenatewas mixed with an equal volume of 4% SDS in H-buffer containing theprotease inhibitor. The samples were then sonicated and centrifuged at100,000×g at 4° C. for 60 minutes. The supernatant of the samples wasthe SDS-soluble fraction. For the SDS-insoluble fraction, the pellet ofthe samples was further re-suspended in 70% FA and centrifuged at100,000×g at 4° C. for 60 minutes. The supernatant was then collectedand neutralized with 1M Tris, pH 11. Both the SDS-soluble andSDS-insoluble fractions were stored at −80° C. until sandwich ELISAanalysis. Aβ level was measured by a human Aβ40 and Aβ42 ELISA kit(Invitrogen) according to the manufacturer's protocol.

The expression level of Aβ42 in serum and in hippocampus thus determinedare summarized in FIG. 4A and FIG. 4B, respectively. The expressionlevels of Aβ42 in both the serum and hippocampus of mice treated withHA-E2 is lower than those in mice treated with E2 alone or vehiclealone.

Example 4

Synthesis of HA-βALA-C17 Estradiol (HA-C17-E2)

In this example, HA-βALA-C17 estradiol (HA-C17-E2) was synthesized inaccordance with Scheme III (FIG. 5 ).

First, estradiol (1.84 mmole, 500 mg) was dissolved in DCM (40 mL) andstirred for 15 minutes. Then, 255 μL of 2.02 mmole benzoyl chloride and5 drops of triethylamine were added to the reaction mixture, which wasthen stirred for 24 hours at 20° C. under nitrogen. The reaction mixturewas concentrated under vacuum and then purified using silica gel columnchromatography (elution: EA/DCM=3/97) to obtain estradiol benzoate(Bz-estradiol).

Next, Bz-estradiol (0.23 mmole, 85 mg) was dissolved in dry DCM (20 mL)and stirred for 10 minutes. N,N′-Dicyclohexylcarbodiimide (DCC) (0.45mmole, 94 mg) and 4-dimethylaminopyridine (DMAP) (0.23 mmole, 27 mg)were added in the reaction mixture, which was stirred for 30 minutes.Thereafter, Boc-β-alanine (0.45 mmole, 87 mg) was added and stirredunder nitrogen for 24 hours at 25° C. The reaction mixture was filteredand the filtrate was extracted using DDW. The organic layer wascollected, and the solvent was removed under vacuum to obtain the crudeproduct, which was then purified using silica gel column chromatography(elution: EA/DCM=3/97) to obtain estradiol-benzoate-Ala-Boc(Bz-Estradiol-β-ALA-boc).

Then, Bz-Estradiol-β-ALA-boc (0.18 mmole, 100 mg) was dissolved in MeOH(5 mL), and the pH was adjusted to 9-10 using 5 M NaOH. The reactionmixture was stirred under room temperature. After 24 hours, the pH ofthe reaction mixture was adjusted to 6 using 50% AcOH, which was thenconcentrated to obtain an oily liquid. The oily liquid was extractedthree times using EA and brine. The water in the organic layer wasremoved using MgSO4, and the solvent was then removed under vacuum toobtain the crude product, which was later purified using silica gelcolumn chromatography (elution: EA/DCM=5/95) to obtain E2-Ala-Boc.

The stepwise procedure for the synthesis of HA-C17-E2 was as follows.Bottle A: HA (0.49 mmole, 200 mg) was dissolved in DDW (20 mL) bystirring for 2 hours, and then DMSO (25 mL) was poured into the reactionmixture under stir until the temperature went back to RT. Bottle B:E2-Ala-Boc (0.10 mmole, 44.1 mg) was dissolved in DCM (2 mL) and thenadded with trifluoroacetic acid (TFA) (1.31 mmole, 0.1 mL). The solutionwas stirred at RT for 2 hours. Thereafter, most of the DCM and TFA wereremoved by concentration, and then DDW (2 mL) was poured into thereaction mixture and the pH was adjusted to 7 using 0.5 M NaHCO₃. DMSOwas added into the reaction mixture until the precipitate dissolved.Oxyma (0.55 mmole, 77 mg) was dissolved in DMSO (4 mL), and the solutionwas then poured into bottle A, which was then stirred for 10 minutes.The solution of bottle B was slowly added into bottle A by pipette, andthe mixture was thoroughly mixed for 15 minutes. DIC (2.58 mmole, 326mg) was added into the mixture under the level by pipette, and thereaction was lasted for 24 hours. After that, the reaction mixture waspurified by dialysis (3,500 MWCO dialysis bag, 5 L of 0.3 M NaCl for 12hours, 6 times; and 5 L of water for 12 hours, 6 times), and then thefraction within the dialysis bag was collected and lyophilized.

The HA-C17-E2 thus synthesized was confirmed by UPLC (data not shown),and the drug load was determined using UV-Vis spectrometer at 280 nm. Inone working example, the DS of the HA-C17-E2 is about 0.54%; in anotherworking example, the DS of the HA-C17-E2 is about 13.55%.

Example 5

Effect of Hyaluronan Conjugates on Cognitive Functions

Prior study has demonstrated that of ovariectomy (OVX) orhysteroovariotomy (OHE) female rats showed a significant decrease indendritic spine of pyramidal neurons in sensorimotor cortex and thehippocampal CA1 region and manifested cognitive deficits, suggestingthat estrogen play some roles in the learning and memory function ofrats.

In this examples, female rats underwent hysteroovariotomy (OHE) weretreated with the present hyaluronan conjugates and then subject to amodified Morrison water maze task to assess the cognitive functions(e.g., learning and memory) of rats.

8 week-old female Sprague-Dawley (SD) rats were used for this study. Allanimals were caged individually in a temperature (24±1° C.), humidity(60%-65%) and light-controlled room (12/12-hour light-dark-cycle) withfood and water ad libitum. All experimental procedures were approved bythe Animal Care and Use Committee of National Chung-Hsing Universityunder guidelines of the National Science Council of Taiwan.

For OHE surgery, the rats were deeply anesthetized with 7% chloralhydrate and 2% xylazine (0.45 mL/100 g body weight) and subjected to OHEsurgery. Two weeks after the surgery, rats were given test drugs twiceweekly for two weeks, and rats were sacrificed four weeks after thesurgery.

Five days before the sacrifice, the modified Morrison water maze taskstarted. The maze consisted of a black circular pool of 145 cm indiameter and 22 cm deep. One visual cue (star cardboards) was located atthe edge of the pool. A round transparent platform was placed 3 cm belowthe surface of the water. Animal performance was recorded with a videocamera and analyzed with the SMART video tracking system (SMART 3.0V,Panlab, Havard Apparatus, Cambridge, UK).

To assess the escape latency, rats were tested with two trials per dayfor 3 consecutive days. Rats were randomly placed at different quadrantof the pool facing the wall of the pool. The rats were allowed to remainon the platform for 60 seconds if it escaped within 180 seconds oralternatively placed on the platform for 60 seconds if it failed tolocate the underwater platform within 180 seconds. A recovery period of10 minutes was allowed between the two trials conducted each day. Theescape latencies of the two trials each day were averaged for subsequentanalyses.

To run the spatial probe test, the platform in the pool was removed andthe pool was planned with a virtual target quadrant and a virtualplatform according to the previous location of the platform. After thefinal escape latency task and a one-day break, the rat was placed intothe diagonal area of the target quadrant facing the wall of the pool.The rat was allowed to swim for 30 seconds and the swimming path wasanalyzed.

All experimental data were expressed as mean±SEM. Statisticalsignificance was tested with one-way analysis of variance (ANOVA)followed by the Student-Newman-Keuls (SNK) post hoc test. Differenceswere considered statistically significant at a p-value <0.05.

In one round of test, OHE rats were treated with 2× E2 (280 ng/kg bodyweight; n=6), 1× HA-C17-E2 (35 μg/kg body weight; DS: 0.54%; equivalentto 140 ng/kg E2; n=5), or 1.5× HA-C17-E2 (5.25 μg/100 g body weight; DS:0.54%; equivalent to 210 ng/kg E2; n=5). OHE rats (n=6) and normal ratswithout OHE surgery (n=4) were used as positive and negative control.

Latency test results summarized in FIG. 6A (swimming distance) and FIG.6B (swimming time) indicate that the OHE surgery adversely affect thelearning function of rats, while the administration of 1× HA-C17-E2,1.5× HA-C17-E2, and 2× E2 may improve the OHE rats' learning abilitywith a statistical significance with respect to the OHE group.

For the spatial probe test, the data provided in FIG. 7A (distance intarget quadrate) and FIG. 7B (time in target quadrate) show that theadministration of 1.5× HA-C17-E2 significantly improved the rat's memoryfunction with respect to the OHE treated group (#, p<0.05) 1× HA-C17-E2group (@, p<0.05) and the 2× E2 group ($, p<0.05). Since the preliminarydata from this example show that 2× E2 is less effective in promotingthe learning and memory function of OHE rats, compared with the 1.5×HA-C17-E2 with only 75% of equivalent E2 with respect to 2× E2, in thesubsequent test, the amount of E2 given to OHE rats was furtherincreased.

In another round of test, OHE rats were treated with 2.5× E2 (350 ng/kgbody weight; n=16) or 1.5× HA-C17-E2 (52.5 μg/kg body weight; equivalentto 210 ng/kg body weight; n=16). OHE rats (n=8) and normal rats withoutOHE surgery (n=8) were used as positive and negative control.

Latency test results summarized in FIG. 8A (swimming distance) and FIG.8B (swimming time) indicate that the OHE surgery adversely affect thelearning function of rats, while the administration of 1.5× HA-C17-E2and 2.5× E2 may improve the OHE rats' learning ability with astatistical significance with respect to the OHE group on day 3 (#,p<0.05).

For the spatial probe test, the data provided in FIG. 9A (distance intarget quadrate) and FIG. 9B (time in target quadrate) show that theadministration of 1.5× HA-C17-E2 and 2.5× E2 significantly improved therat's memory function with respect to the OHE treated group (#, p<0.05).

It should be noted that in the second round of experiments, the ratstreated with 1.5× HA-C17-E2 or 2.5× E2 both show significant improvementin cognitive functions; however, the amount of the equivalent E2 in the1.5× HA-C17-E2 treatment is only 60% of that in the 2.5× E2 treatment.

Example 6

Effect of Hyaluronan Conjugates on Dendrite Number and Spine Density

The rats were deeply anesthetized with 7% chloral hydrate and 2%xylazine (5 mL/kg body weight) and fixed on the dissection table. Tissuepreparation for intracellular dye injection and immunohistochemicalstaining were performed as follows. Briefly, rats were transcardiallyperfused with 2% paraformaldehyde in 0.1 M phosphate buffer (PB), pH7.3, for 30 minutes. Brains were carefully removed and sectioned withvibratome (Technical Products International, St. Louis, Mo.) into twoparts: (1) two pieces of 350-μm-thick coronal slices contain hippocampusfor intracellular dye injection; (2) 1000-μm-thick coronal slicescontained medial septal (MS) nucleus and 2000-μm-thick coronal slicescontained hippocampus for immunohistochemical staining. The thick slicesfor immunohistochemical staining were postfixed in 4% paraformaldehydein 0.1 M PB for 1 day. The slices for intracellular dye injection weresoaked in 10-7 M 4′,6-diamidino-2-phenyl-indole (DAPI; Sigma-Aldrich,St. Louis, Mo.) in 0.1 M PB for subsequent processes. The fresh braintissue containing forebrain basal nucleus, cerebral cortex, andhippocampus were taken by decapitation. The brain tissue was stored in a−70° C. refrigerator for subsequent protein quantification.

FIG. 10A and FIG. 10B respectively show the photographs of distal apicaldendrite and basal apical dendrite in rats. As could be seen in thedrawings, OHE rats have less dendrites, compared to control rats that donot undergo OHE surgery. On the other hand, rats treated with 2.5× E2and 1.5× HA-C17-E2 have more dendrites, compared to OHE treated rats.

The quantitative results in FIG. 11A (apical segments) and FIG. 11B(basal segments) indicate that OHE surgery is associated with a decreasein spine density, compared to control rats (*, p<0.05). On the otherhand, although the administration of 1.5× HA-C17-E2 and 2.5× E2 bothresult in a significant improvement of the spine density, compared toOHE rats (#, p<0.05), the rats treated with 1.5× HA-C17-E2 have aslightly higher spine density with respect to rats treated with 2.5× E2.It is unexpected to see this result, considering the fact that theamount of estradiol given to the 1.5× HA-C17-E2 treated group is only60% of that given to 2.5× E2 treated group.

The dorsal hippocampus was randomly chosen three sections in each rat.To determine the density of dendritic spines in hippocampus, distalapical and distal basal dendrites of CA1 pyramidal cell was analyzed.Five independent cells of the hippocampal CA1 region and 3 segments fromeach dendrite were randomly counted per 10 μm. All data were expressedas mean±SEM. Statistical significance was tested with one-way analysisof variance (ANOVA) followed by the Student-Newman-Keuls (SNK) post hoctest for the spine density. Differences were considered statisticallysignificant at p<0.05.

Example 7

Effect of Hyaluronan Conjugates on Sensorimotor Function

In this example, the pole and beam traversal test (pole test) wascarried out to assess the effect of the present hyaluronan conjugate onthe sensorimotor function of mice.

8 week-old male C57BL/6 mice (n=4-5 per group) purchased from BioLASCOTaiwan Co., Ltd were used for this study. All animals were cagedindividually in a temperature (24±1° C.), humidity (60%-65%) andlight-controlled room (12/12-hour light-dark-cycle) with food and waterad libitum. All experimental procedures were approved by the Animal Careand Use Committee of National Chung-Hsing University under guidelines ofthe National Science Council of Taiwan.

Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 20 mg/kg) wasintraperitoneally (i.p.) administered to mice four times a day at a2-hour interval on the 1st and 5th day in the MPTP-induction group. 5×E2 (342 ng/kg) and 2.5× or 5× HA-C17-E2 conjugate (1.96 or 3.92 μg/kgbody weight; DS: 13.55%; equivalent to 171 or 342 ng/kg E2) wereintravenously (i.v.) administrated to the experimental animal on the 2ndday and 6th day. The Sham group was treated with either intraperitonealinjection of saline or intravenous injection of PBS buffer in the sameway.

The mice were subject to a pre-test two days before the MPTP-induction,and on day 2 and day 6, the pole test was carried out 4 hours after thedrug administration. Briefly, a tube of 50 cm in length and 1 cm indiameter was used, and a pole was attached to the top of the tube.Animals will often naturally orient themselves downward and descend thelength of the pole in order to return to their home cage. The micereturning to their home cage by climbing were given a score of “0”. Onthe other hand, the mice who failed to turn and instead kept their bodyin a position horizontal to the pole and climbed down often in acorkscrew-like manner were scored “1.” Results were analyzed using theChi-Squared test of independence in IBM SPSS Statistical 20.0 software;significance was set at p<0.05.

The results summarized in FIG. 12 indicate that the MPTP inductionadversely affect the motor coordination function of mice (*, p<0.05),and the administration of 5× E2 does not effectively improve the motorcoordination function of MPTP-treated mice. In contrast, theadministration of 2.5× or 5× HA-C17-E2 significantly improve the motorcoordination function of MPTP-treated mice (*, p<0.05).

The above examples provide several in vitro and in vivo test results,which establish that the present hyaluronan conjugates are capable ofpromoting the dendritic spine density, improving cognitive functions(such as learning and memory), and boosting sensorimotor functions.Taken together, these experimental data demonstrate that the presenthyaluronan conjugates indeed could prevent the manifestation ofneurodegeneration in mice and rats, thus may serve as a prominentcandidate for developing a medicament for treating a neurodegenerativedisease such as Alzheimer's disease, Parkinson's disease, amyotrophiclateral sclerosis, multiple sclerosis, Huntington's disease,frontotemporal dementia, epilepsy, neuropathic pain, or ataxia.

It will be understood that the above description of embodiments is givenby way of example only and that various modifications may be made bythose with ordinary skill in the art. The above specification, examplesand data provide a complete description of the structure and use ofexemplary embodiments of the invention. Although various embodiments ofthe invention have been described above with a certain degree ofparticularity, or with reference to one or more individual embodiments,those with ordinary skill in the art could make numerous alterations tothe disclosed embodiments without departing from the spirit or scope ofthis invention.

What is claimed is:
 1. A hyaluronan conjugate, comprising: a hyaluronicacid (HA) or salt thereof; a sex hormone, selected from the groupconsisting of, estrone, estradiol, estriol, testosterone, and11-deoxycorticosterone; and a linker, covalently coupling the sexhormone with one of the disaccharide units of the HA or salt thereof,wherein the linker is selected from the group consisting of, one or moreβ-alanine (β-ALA), lipid, dihydrazide-C₂-C₂₀ dicarboxylic acid, andC₂-C₂₀ dicarboxylic acids.
 2. The hyaluronan conjugate of claim 1,wherein the hyaluronan conjugate has a degree of substitution with thesex hormone of 0.1 to 60%.
 3. The hyaluronan conjugate of claim 1,wherein the HA or derivative or salt thereof has a weight-averagemolecular weight (Mw) of about 5 to 500 kilodaltons (kDa).
 4. Thehyaluronan conjugate of claim 2, wherein the linker is covalentlycoupled to the hydroxyl group (—OH) of the sex hormone.
 5. Thehyaluronan conjugate of claim 1, wherein the dihydrazide-C₂-C₂₀dicarboxylic acid is adipic dihydrazide (ADH)-succinate.
 6. Thehyaluronan conjugate of claim 1, wherein the C₂-C₂₀ dicarboxylic acidsis succinic acid.
 7. A pharmaceutical composition for treating aneurodegenerative disease, comprising an effective amount of ahyaluronan conjugate according to claim 1 and apharmaceutically-acceptable excipient, wherein the neurodegenerativedisease is Alzheimer's disease (AD), Parkinson's disease (PD),amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS),Huntington's disease (HD), frontotemporal dementia, epilepsy,neuropathic pain, or ataxia.